IMMUNOLOGICAL UNRESPONSIVENESS IN ALLERGIC CONTACT DEMATITIS TO DINITROCHLOROBENZENE IN GUINEA PIGS

Effects of immunological responsiveness on Langerhans cell behavior in contact sensitization

The epicutaneous application of haptens results in a functional activation of the antigen-presenting Langerhans cells (LCs) which is necessary for the induction of contact sensitivity. In this ultrastructural study, we investigated the effects of the immune response on these cellular properties of the LCs by using 2 strains of guinea pigs with genetically determined high and non responsiveness, respectively, to the strong sensitizer 2,4-dinitrochlorobenzene (DNCB). After skin painting, both strains showed a similar cellular and endocytotic activation of the LCs and a similar intraepidermal localization of DNCB on immunoelectron microscopical visualization. There were however few LC-lymphoid cell interactions in the non responders, in contrast to numerous such appositions in the other strain. Intravenous tolerization with 2,4-dinitrobenzene-1-sulfonic acid, which is known to block the DNCB receptor of T cells, hampered the lymphoid cell interactions in the DNCB treated high responders, but it did not affect the LC activation. These in vivo observations demonstrate that the hapten-induced changes of the LC properties is the initial, T-cell independent event in contact sensitization.

Selection of the delayed hypersensitivity T effector and T suppressor cell response by antigen-presenting macrophages

The T effector lymphocytes of delayed type hypersensitivity reactions (TDH) are regulated by a complex T suppressor (Ts) cell circuit. Induction of TDH cells requires Ia+ adherent cells as antigen-presenting cells. Little is known about the antigen presentation of the induction of Ts cells. We describe an experimental model in which TDH and Ts cells are induced separately by different antigen-presenting macrophages grown from bone marrow stem cells. Bone marrow derived macrophages grown in L cell-conditioned medium for various periods and labeled with 2,4-dinitrobenzene sulfonic acid differ in their ability to induce TDH and Ts cells in vitro. The functional activity of the two T subpopulations was assessed in vivo by epicutaneous challenge or sensitization with 2,4-dinitrofluorobenzene of mice receiving the in vitro educated cells. Ear swelling or suppression of swelling was recorded. It could be shown that 5-7 day bone marrow-derived DNP-labeled macrophages preferentially induced Thy 1+ Lyt 1+ antigen-specific TDH cells; 7-10 day old antigen-presenting bone marrow-derived macrophages induced preferentially Thy 1+ Lyt 2+ antigen specific Ts cells. Characterization of various phenotypic markers revealed different surface antigen expression and functional differences such as MIF responsiveness or transglutaminase activity on the two macrophage populations. These data support the concept that activation of the Ts regulatory circuit may require antigen presentation by specialized antigen presenting cells, characterized by certain surface and functional markers and different from those inducing preferentially TDH cells.

Immunologic unresponsiveness induced by topical application of hapten to PUVA-treated skin in guinea pigs

Pretreatment by topical application of 8-methoxypsoralen and subsequent exposure to long-wave ultraviolet light (PUVA) on the induction site of contact sensitization to dinitrochlorobenzene (DNCB) significantly diminished the challenge reactions in guinea pigs. A single treatment with PUVA in a small area was enough to exhibit such an effect. Furthermore, the animals that had been first exposed to DNCB through PUVA-treated skin failed to become sensitized to the subsequent sensitization regimen of the same hapten even through previously untreated skin. The unresponsiveness in these animals was hapten-specific, since their capacity to become sensitized to an unrelated hapten, oxasolon, was not impaired. The intraperitoneal administration of cyclophosphamide at a dose of 200 mg/kg shortly before contact sensitization reversed the unresponsiveness in tolerant animals. These findings suggest that tolerance in these animals is a specific immunologic unresponsiveness mediated by suppressor cells.

Suppression of contact sensitivity by IgG1 antihapten antibody in contact-sensitized guinea pigs

The guinea pig sera obtained 2 weeks after 1-fluoro-2,4-dinitrobenzene sensitization had ability to suppress elicitation of contact sensitivity when transferred intravenously into contact sensitized guinea pigs. The activity was found only in the sera obtained 2 weeks after the sensitization, whereas the sera obtained 1 and 3 weeks after the sensitization had no effect on contact sensitivity. Pretreatment of cyclophosphamide abolished the generation of the suppressive factor. The suppressive factor was hapten-specific. It was eluted from a Sephadex G-150 column into 7S gamma-globulin fraction and from DEAE ion exchange cellulose column into IgG1 fraction. The suppressive activity was absorbed on a dinitrophenylated bovine gamma globulin Sepharose 4B column and was eluted by either acidic buffered solution or dinitrophenol from the affinity column. It was absorbed by antiguinea pig IgG1-Sepharose and not by antiguinea pig IgG2-Sepharose, Therefore, the suppressive activity found in the sera of 1-fluoro-2, 4-dinitrobenzene sensitized guinea pigs was attributed to IgG1 antihapten antibody.

Allergic contact dermatitis in the hamster

Allergic contact dermatitis to strong, low molecular weight contact allergens can regularly be induced in the hamster. By its clinical course, histopathology and susceptibility to intensification with complete Freund's adjuvant, this hypersensitivity appears congruent with the allergic contact dermatitis observed in other experimental animals and the allergic contact dermatitis seen in humans. Further, in the hamster, we find that pretreatment with cyclophosphamide intensifies the acquisition of allergic contact dermatitis to dinitrochlorobenzene and to oxazolone; the target of cyclophosphamide immunopotentiation has been shown in the mouse and guinea pig to be a regulator suppressor cell. In addition, we have induced in the hamster specific immune tolerance to dinitrochlorobenzene with dinitrobenzene sulfonate; in the mouse and guinea pig it has been demonstrated that the induction of specific immune tolerance to contact allergens by parenteral hapten involves the elaboration of specific suppressor cells. These findings, then, imply the existence of regulatory suppressor cells for T-cell phenomena in the hamster. This contrasts with reports that suppressor cell function in hamsters, as against other rodents, is defective as it relates to the regulation of, for instance, allogeneic reactions, antibody formation and tolerance to contact allergens.

Mechanism of reappearance of contact sensitivity to DNCB in desensitized guinea pigs

The different immunologic activities of lymph node and spleen cells as compared to peritoneal exudate cells were studied in temporarily desensitized, DNCB-contact-sensitive guinea pigs. Lymph node (and spleen) lymphocytes: (a) transfer contact sensitivity to syngeneic recipients when harvested at the time of unresponsiveness; (b) are only temporarily inactivated in tolerant recipients by the desensitizing procedure; (c) enter the lymph node (or spleen) compartments in a higher proportion than peritoneal exudate cells; (d) are not susceptible to inactivation in vitro; and (e) are not permanently desensitized when released into the circulation by an intravenous injection of Bordetella pertussis vaccine. These results indicate that the resistance of primed lymph node cells to the desensitizing procedure may account for the reappearance of contact sensitivity in desensitized guinea pigs.

Differing mechanisms of tolerance and desensitization to dinitrochlorobenzene in guinea pigs

In the present paper the mechanisms of tolerance and desensitization to dinitrochlorobenzene (DNCB) contact sensitivity in guinea pigs were investigated using the methods of adoptive sensitization of tolerant and normal syngeneic recipients and cyclophosphamide-treatment of tolerant animals known to selectively inactivate suppressor lymphocytes. It was shown that desensitization of presensitized animals is caused by the direct effect of the intravenously injected hapten on the effector cells in the peripheral compartment. The immediate onset of unresponsiveness and its very short duration almost exclude the possible involvement of enhancing antibodies or suppressor cells. In the case of tolerance induced by pretreatment with dinitrobenzenesulfonic acid, suppressor cell activity is enhanced, preventing normal specific immunocompetent cells from recognizing the antigen and/or proliferating in the draining lymph nodes. Whether suppressor lymphocytes are of the B or T type is not yet known.

Immunological Tolerance Induced in Animals Previously Sensitized to Simple Chemical Compounds

Adult guinea pigs develop a delayed hypersensitivity to intradermally injected neoarsphenamine. If the animals are treated intravenously with high doses of this compound before sensitization, a specific and permanent immunological tolerance develops. Permanent tolerance is also obtained in previously sensitized animals when an intravenous injection of neoarsphenamine isfollowed 6 hours later by an intradermal one. When, however, the interval between the two injections is extended to 7 or 14 days, no tolerance is observed.